Multi-channel audio signals provided via digital versatile discs (DVD), Blu-ray discs (BD), digital television broadcasting, and so on are output from corresponding speakers each of which is placed at a predetermined position in an acoustic space, so as to implement audio reproduction with stereophonic perception. Such stereophonic perception can be obtained when the human auditory perception is made to perceive a sound source that actually does not exist as if it exists in an acoustic space. The sound source as in such a phenomenon is referred to as “sound image”, and feeling as if the sound source exists is called “a sound image is localized”.
Meanwhile, aside from the speaker systems that reproduce multi-channel audio signals, there is the case where plural speakers having different frequency characteristics are combined for use in a speaker system which includes plural speakers. This can be seen, for example, in the case where a speaker system including plural speakers is placed in a limited space such as a home.
In order to clear the limitation of placement space in a room such as that in a home, using a small speaker or a headphone instead of a large broadband speaker is effective. However, such a small speaker has frequency characteristics that a sound pressure level of a sound in a low-frequency range is lower than that of a large diameter speaker. In view of the above, a subwoofer speaker is provided, in order to compensate a bass sound pressure level, to the conventional speaker systems in which a small speaker is used.